Vista Welcome Screen is black

About a month ago, I shut down my computer for an update. When it restarted, there were some issues that eventually dissolved into a black screen only. I had already contacted Crucial re: memory messages coming up and discovered I was to have manually reset the memory voltage for the 2.2V sticks. They suggested I return them as they could be damaged. When this happen, it was natural to make that jump.

Time got away from me and I just now got my replacement sticks. I installed them and went in to BIOS first off and manually set the voltage - the sticks are now offered at 2.0V instead of 2.2V, but that's another issue. Anyway, it started through the process to the screen asking how to start - I chose Safe Mode. It goes to the screen that shows the green bars of MS loading and then - black screen...AGAIN.

Since I now know this is NOT a memory issue, I went online and discovered that many people are having the same problem. After a Windows update, when their computer restarts, problems occur and eventually the Welcome Screen is replaced by a black screen. Many people are posting this problem but no one has a solution, including Microsoft.

My next step was to go to MS but, since the losers and their defective products are only covered for 90 days, at 4 1/2 months, I can't use this option without paying $59+tax - FOR THEIR MISTAKE! I did find a little blurb on this issue and MS says they are aware of it (for over a year) and the only option is to do a reinstall of the OS. They also mention that this problem was related to a particular file or something other but that they fixed it with the SP1. Since my virgin build has only had the Vista Home Premium 64bit SP1 on it, this is obviously NOT fixed. Not that I can even tell MS that much!

So my questions are as follows:

1) What do I lose with a reinstall? Program files? Data files? Game files? My Virus software?

2) Vista and my virus software come with 3 keys. I had to reinstall Vista 1 day after installation because it went blue screen. This will be my third install. That means no more keys so, next time my computer screws up because of MS updates, I'll have to pay. It will be my 2nd with Kaspersky - not a cheap software. Is there any way to contact MS about this so that I can get future keys at no additional cost?

3) When I reinstalled Vista all those months ago, it kept the only install as WINDOWS.OLD, or something like that. Since it was a brand new install and I had very little loaded, I simply deleted that file. Assuming it does that again this time, is there a way to get programs and files from the "old" to the "new"?

4) Any tips on contacting MS without being charged? I want some sort of assurance on how to handle future updates, in case it happens again. The problem is System Restore, Safe Mode, etc., don't work with this issue. It is something that affects the Welcome Screen, turning it black and making it impossible to log in to affect any changes at all.

5) Any one here who's had this problem found a better solution that reinstalling? If you did reinstall, how did it work for you?

Thanks to everyone for looking at this issue. I did do a search here - so many Vista issues - and, while it seems a black screen occurs for many, it does so under many different circumstances. It was mentioned elsewhere that it happened after an update and, in hindsight, I recall the same event, as I rarely turned off my computer.